ME:A takes place 600 years after ME. The ships even leave the Milky Way at least 1 Year befor ME:3 starts..... so if no Light-Head hide himself in one of the ships, it is quite unlikely that they will show up except in cameos...

All i can point it to are the breadcrumbs in the current timeline. The Nexus, Hyperion aso start somewhat in the Autumn of 2185.... where as the Arrival DLC occurs in March 2186. It is stated, that the Reaper Invasion started on 21th September 2186 (Cerberus Network News), so 6 Months earlier.

So the Geth Missions of ME 2 might have happened by the time ME:A is "launched", but they do not matter.

ME 2 takes place in the the Terminus Systems, while the Andromeda Initiative is a pure Citadel Space endeavour. Except for some folks like Hackett, Anderson or the Council no one knows what Shep did with the Collectors. The News mentioned the attack on Horizon, but not that someone managed to save 2/3 of the colonists.

As far as Andromeda knows.... they are still there, but "not quite the bogeyman they used to be". No Sir, no carry over here.

Also, the four Ark Ships are esssntially geared for each Council Race, and it would seem the Krogan are there just as hired muscle. I think the actual launch of the Ark Ships occurred between ME2 and ME3, but it may have happened during some of ME2. Nevertheless, regardless of your choices as Shepard, there are no healthy, cooperative relationships between the Geth and other races at this point. Besides the Council races and the Krogan, it is not likely that any other races will be featured, beyond the previously mentioned cameos. In better news, it does seem like we have a female Turian in the crew.

As far as I've been aware, female Turians are still soldiers. I'm not sure why BioWare left them out. Also, although seen as precious resources, female Krogans are still fierce warriors, but they don't normally leave the homeworld.